Soybean production has become a significant force for economic development in Brazil, but has come at the cost of expansion into non-protected forests in the Amazon and native savanna in the Cerrado. Over the past fifty years, production has increased from 26 million to 260 million tons. Area planted to soybeans has increased from roughly 1 million hectares in 1970 to more than 23 million hectares in 2010, second only to the United States.
An accurate estimate of carbon fluxes associated with tropical deforestation from the last two decades is needed to balance the global carbon budget. Several studies have already estimated carbon emissions from tropical deforestation, but the estimates vary greatly and are difficult to compare due to differences in data sources, assumptions, and methodologies. In this paper, we review the different estimates and datasets, and the various challenges associated with comparing them and with accurately estimating carbon emissions from deforestation. We performed a simulation study over legal Amazonia to illustrate some of these major issues. Our analysis demonstrates the importance of considering land-cover dynamics following deforestation, including the fluxes from reclearing of secondary vegetation, the decay of product and slash pools, and the fluxes from regrowing forest. It also suggests that accurate carbon-flux estimates will need to consider historical land-cover changes for at least the previous 20 years. However, this result is highly sensitive to estimates of the partitioning of cleared carbon into instantaneous burning vs. long-timescale slash pools. We also show that carbon flux estimates based on 'committed flux' calculations, as used by a few studies, are not comparable with the 'annual balance' calculation method used by other studies.
Senior Fellow, Emerita, Stanford Woods Institute and Freeman Spogli Institute for International Studies,
William Wrigely Professor, Emerita, Department of Environmental Social Sciences
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PhD
Rosamond (Roz) Naylor is the William Wrigley Professor, Emerita, of Global Environmental Policy in the Doerr School of Sustainability; and founding Director of the Center on Food Security and the Environment (FSE) at Stanford University. Her research focuses on policies and practices to improve global food security and protect the environment on land and at sea. She has been involved in numerous field-level research projects around the world with her students and has published widely on issues related to global food systems, food policy, and aquaculture. She is the co-chair of The Blue Food Assessment, an international initiative aimed at providing a comprehensive scientific evaluation of the sustainability, nutrition, equity, and justice dimensions of aquatic foods cultured and captured in freshwater and marine environments within the global food system. She is a Member of the National Academy of Sciences, a Fellow of the American Association for the Advancement of Science (AAAS), Fellow of the Ecological Society of America (ESA), a Pew Marine Fellow, and a Leopold Leadership Fellow. She is also the Chair of the Board of Directors for the Aspen Global Change Institute and a member of the Scientific Advisory Committee for Oceana. At Stanford, she teaches courses on The World Food Economy, Human Society and Environmental Change, and Food and Security.
